Pressure fluid gauge



1938- w. H. LONGSTREET 2,128,619.

PRESSURE FLUID GAUGE Filed June 25, 1957 Z w H W Patented Aug.30, 19 38 I 2,128,619

UNITED STATES PATENT OFFICE PRESSURE FLUID GAUGE Walter H. Longstreet, Brooklyn, N. Y., assignor to Acme Air Appliance Company, Inc., Brooklyn, N. Y., a corporation of New York Application June 23, 1937, Serial No. 149,983 2 Claims. (01. '73-111) The present invention relates to improvements the novel features thereof defined by the apin pressure fluid gauges and more particularly to pended claims.

that type disclosed in my prior Patent No. 2,078,- In the drawin 143, d t April 20, 1937. Fig. 1 is a longitudinal sectional view of an In the prior devices of this type, it has been embodiment O y inVentiOn;

the universal custom to provide the plunger with Fig. 2 is a greatly enlarged fragmentary seca flexible cup washer of'leather to prevent leaktional view of the chuck end of the gauge just age of the pressure fluid operating against the e e he Chuck s rewed ho e; plunger. The useful or effective life of these Fig. 3 is a detail view of the sp a e member washers is comparatively short due to their abused in my invention; 0 sorptive characteristic and tendency to dry out. 4 a et ew Of e plun r S o n Neatsfoot oil, generally used to preserve the the p Washer in o leather, penetrates the pores and dirt becomes Fig. 5 is a bottom plan View O t e Spreader embedded in. the leather, setting up wear which mber; and 15 soon causes variation and inaccuracy of the F g.6 is a p plan View Of the p 15 gauging function, h gauge ha m b t orig- Like reference characters designate correinaliy to compensate for this wear, but further sp nd n parts in the S veral figures of the drawthan this, the oil has a tendency to leak past ing. the plunger and to get on the gauge bar before Ref o e dr w l indicates the W the instrument is sold. In this condition of soil, i de o housin of the au e havin one end purchasers refuse t b resulting i the ret thereof externally threaded to receive the inof many for replacement. ternally threaded air chuck 2. Within the hous- Furthermore, in the course of time, the leather ing is mounted the gauge bar 3, suitably calibecomes dry, and tends to shrink away and curl brated as customary and slidable through the rein from contact with the cylinder wall, allowing tai-nerthimble 5, which is held in place by spin- 25 pressure fluid to pass and destroying accuracy ning the end of e cy er inwa d y a st of the instrument. the reduced wall 5' of said thimble.

These washers cannot readily be replaced due Within the casing is the usual plunger return to the manner of assembly of the parts, and spring 6 which ,acts to hold the thimble 5 seated factory servicing is impracticable due to expense and the pl r 1 in its normal position shown 30 in time and labor, having regard for the selling in Figs. 1 and 2. price of the article. The gauge bar 3 as usual coacts with the The purpose of the present invention, thereplunger l which is of the special construction fore, is to overcome these difliculties by the p-ronow to be set forth. The plunger comprises a vision of a new type of plunger characterized metal body of a dimension at one end to fit in 35 particularly by the use of a mouldable oil proof the end of the spring 6. At its upper portion is washer, unaffected by heat, oil or the presence formed an annular collar 8 constituting a spring of foreign matter, while maintaining its flexibilseat at one side. Above the collar, the diameter ity and effectiveness against leakage of the presis reduced and again flares outwardly to form a sure fluid past the plunger. top collar or flange 9 relatively smaller than the 40 Owing to the mouldability of the washer, it is collar 8. This produces an annular V-shaped found possible to make the plunger a unitary groove between the collars. structure, greatly facilitating the manufacture About this upper end is moulded a cup washer and assembly of the parts, in addition. tothe of oil-proof material in the nature of synthetic prolongation of life and accuracy of the instrurubber, such as Duprene or the like, noted for ment due to the nature of the material used. its resiliency or rubber-like characteristics, its A further object of my invention is the proviability to withstand heat and resistance to swellsion of a spreader member, functioning not only ing when boiled or soaked in oil or water. to maintain the plunger skirt in proper position As seen best in Fig. 4, the washer is formed to receive the pressure fluid, but also serving with a depression ill, the base of which is a sub- 50 to establish an interlocking engagement of the stantial thickness of the substance seated on and air chuck and cylinder or housing in the assembly attached to the head of the body, which supports operation. the walls of the cup against collapse when sub- Other and further objects and advantages of jected to pressure. The walls of the cup at the the invention will be hereinafter set forth and top taper to a thin skirt or lip, while the exterior 55 of the cup tapers toward the collar 8. The diameter at the top just fits the interior diameter of the cylinder so that only this extreme lip contacts with the cylinder, eliminating drag on the cylinder wall in the movements of the plunger.

The attachment of this cup washer by vulcanization and structural inlock with the body produces an integral unit with a flexible lip of long life and wearproof material which maintains accuracy of gauging throughout service.

I preferably employ in combination with this plunger a spreader unit or disk I I having a tapering or conical lower end,.as indicated at l2, and an air passage I3 therethrough. This member serves several important functions. The diameter of the disk is slightly larger than that of the cylinder so as to seat on the entrance to the latter in such position that the taper l2 projects into the cup l and acts as a stop to prevent pressure of the spring from causing the skirt to be deformed.

The taper portion, therefore, coacts with the flexible lip of the washer and tends to hold this lip in contact with the wall of the cylinder as long as the plunger is in its uppermost position. Under this condition, no accidental curling in of the washer member is possible at the time the pressure is applied to the plunger and the pressure itself maintains this position of the lip after the plunger leaves the initial position, thereby insuring against leakage of the pressure medium past the plunger in the operation of gauging. Owing to the cooperation of the taper l2 with the recess of the washer, the plunger is maintained centralized.

A further function of this member takes place in the assembly operation of the gauge. As the chuck 2 is screwed into its final position, it contacts with the top of the unit II and further slight pressure tends to press the entrance of the cylinder outwardly suificiently to establish an interlock with the internal thread of the chuck and this practically prevents any possibility of accidental unscrewing of the chuck. As a matter of fact, tests prove that it is very diflicult to unscrew this chuck after the action above described even with a tool. Obviously, this is a simple expedient for locking the parts of the gauge device in the barrel by means of the spreader unit.

In the use of the gauge, the chuck is applied to the tire nipple in the usual manner to unseat the valve in the chuck and admit air through the chuck passage 2' and passage I3 of the spreader member. The pressure of the fluid medium then moves the plunger down the cylinder against the tension of the spring 6, carrying with it the gauge cated conical portion bar which is projected from the end of the case through the thimbie 5. at the lower end of the same. The indicia on the gauge bar will give the pressure reading.

Removal of the gauge device from the tire stem allows the plunger to return to its normal position under the action of the spring 6, while leaving the bar in its outward position for reading purposes. A slight pressure on the bar will return it to its innermost position cooperating with the plunger, as shown in Fig. 1.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a pressure fluid gauge, the combination of a cylindrical casing, an air chuck having a sleeve extension adapted to fit over the outer extremity of the casing, a plunger member in said casing having a flexible skirted cup-shaped washer secured to and enclosing one side of the plunger, a separate spreader unit having a trunfor engaging the mouth of the casing to expand the same into tight engagement with the sleeve extension when the casing and air chuck portions of the gauge are put together, said conical portion constituting spreading means normally engaging the free extremity of the skirt to hold the same against the inner wall of the casing, the truncated portion of said spreader constituting stop means for limiting the spreading action aforesaid by engagement thereof with the portion of the washer enclosed by said skirt.

2. In pressure fluid gauges, the combination of a cylindrical casing, an air chuck connected to one end of said casing, a plunger member in said casing having a flexible skirted washer attached thereto, and a spreader unit seated on the end of the casing and held by the air chuck, said unit having a tapered extension cooperating with the skirt of the Washer to normally hold the latter against the Wall of the casing and the plunger centralized in the casing, including separate engaging means for limiting the degree of co-operative engagement of the skirt with the spreader unit, said spreader unit comprising a body having greater diameter than the casing and arranged to be clamped against the end or the same by the air chuck, said unit tapering extension being arranged for forcing the end of the casing to expand into engagement with the air chuck to establish an interlock between the chuck and casing, said tapering extension also cooperating with the skirt of the washer to prevent leakage of pressure past the plunger.

WALTER H. LONGSTREET. 

